The present invention relates to a method for detecting a magnetic field by placing part of a core excited beforehand in a magnetic field under measurement and utilizing a variation in a magnetic flux resulting from the magnetization of the part of the core.
A typical example of magnetic field detecting methods which have heretofore been known to the art is a method utilizing a Hall element. The prior art method is adapted to detect an external magnetic field from a Hall voltage obtained by the intensity of the magnetic field passing through the Hall element. However, since a Hall element has a very inferior temperature characteristic and is instable in environmental temperatures and since it is difficult to manufacture a Hall element having a large area, the prior art method is not suitable for the detection of a magnetic field over a wide range and is restricted in its own use.